Silencer and lubricant trap for air tool exhaust

ABSTRACT

A combined baffle and air turbulator-lubricant interceptor gap is mounted within the upper part of a cup defining an expansion chamber and subjacent lubricant sump. The baffle directs exhaust air from a pneumatic tool into circumferential, lubricantdepositing impingement against the wall of the expansion chamber. The turbulator-interceptor gap prevents lubricant from being propelled along interior surfaces to the outlet. Engaged-base double cones of porous sintered metal in the outlet muffle the sound of the outgoing air by breaking up its flow into myriad paths.

United States Patent [191 Thrasher Nov. 5, 1974 SILENCER AND LUBRICANT TRAP FOR AIR TOOL EXHAUST George E. Thrasher, Pontiac, Mich.

Master Pneumatic-Detroit, 1nc., Sterling Heights,.Mich.

Filed: June 4, 1973 Appl. No.: 366,449

inventor:

Assignee:

U.S. Cl 181/36 R, 55/276, 55/337, 181/36 A Int. Cl. F0ln 3/06 Field of Search 55/276, 337, 413, 414, 55/449, 456; 181/36 R, 36 A, 36 C, 57, 58,

' References Cited UNITED STATES PATENTS 4/1932 Woodford 181/36 C UX 4/1947 Tabbert 181/36 C UX 4/1970 Veres et a1 1 55/337 X 12/1970 Pickle 181/36 A 7/1972 Blatt et a1. 181/63 FOREIGN PATENTS OR APPLICATIONS 885,535 12/1961 Great Britain ..2l0/304 1,107,367 5/1961 Germany .55/413 Primary ExaminerRichard B. Wilkinson Assistant Examiner.lohn F. Gonzales Attorney, Agent, or Firm- Barnes, Kisselle, Raisch 8L Choate [57] ABSTRACT 16 Claims, 5 Drawing Figures SILENCER AND LUBRICANT TRAP FOR AIR TOOL EXHAUST This invention relates to a device for removing lubricant from air exhausting from a pneumatic motor and for muffling the sound of the exhaust air.

Pneumatic motors such as cylinders powered by compressed air are lubricated to insure free movement of their pistons within the cylinder walls. It is customary to exhaust such cylinders directly to atmosphere during the course of their cycling. The compressed air tends to exhaust explosively which involves two undesirable results. One, a fog of lubricant is blown out of the cylinder into the atmosphere and two, the air exhausts with a relatively sharp report. The lubricant-contaminated air and loud noise are at best unpleasant and frequently cates with the inlet. Passageway 46 opens downwardly sion chamber for air entering it from passageway 46, 48

and the lower interior portion of the cup forms a sump chamber 54 for collection of trapped lubricant, the level of which is represented at L. A baffle 56 seats on w an annular shoulder 58 in the cup wall. The baffle has constitute health hazards, especially when the equipment is operating within a factory or other enclosed space. with human occupants.

Standards adopted by governmental agencies and by industry now require typically that 90 per cent of the lubricant in the exhausting air be removed before the air is dischargedto the atmosphere and that the sound of the exhausting air be-muffled to a maximum peak impact, A scale, of from 106 decibels to 140 decibels depending upon the particular standard or regulation involved. In addition, the air must be permitted to exhaust rapidly to facilitate cycling of the air motor at normal industrial rates. For example, one large manu- Nfacturer specifies that equipment for removing lubricant and muffling the exhaust air shall permitthe air to exhaust from a tool inless than l3 cycles, i.'e., less than 13/60 seconds. These various requirements tend to work against each other.

The object of the present invention is to provide a relatively simple, inexpensive exhaust air silencer and lubricant remover which is improved to meet all of the requirements discussed above. One form of the invention is shown in the accompanying drawings.

FIG. 1 is an elevational view illustrating an air cylinder and valve in assembly with a silencer and lubricant remover according to the present invention.

FIG. 2 is an enlarged scale central vertical sectional view of the silencer and lubricant trap with parts broken away to illustrate structural detail. I FIG. 3 is afragmentary plan view of a baffle ring. FIG. 4 is a fragmentary enlarged scale elevational view taken'in the direction of arrow 4 of FIG. 3.

FIG. 5 is a sectional view on line 55 of FIG. 2. Shown in FIG. 1' is an air cylinder having a conventional piston (not shown) to which a piston rod 12 is connected. Cylinder 10 has a head 14 pneumatically connected with a valve 16 by an air line 18. Valve 16 is operable to admit air under pressure from an airline 20 to cylinder head 14 and to exhaust air from the cylinder into an exhaust air line 22. A silencer and lubricant trap 24 according to the present invention is connected with exhaust line 22.

Device 24 has a body 26 comprising a head 28 and acup 30. The head and cup are secured together by means of ring 32 threaded onto the head at 34 and having an inward flange 36 which engages the bottom of an outward flange 38 on the cup. Flange 36 clamps flange 38 against a'sealing washer 40 which is in turn clamped against a downwardly facing shoulder 42 on I head 28.

slot-like openings 60 through which lubricant drains downwardly from expansion chamber 52 into sump 54. The baffle shields lubricant in the sump chamber from the flow of air enabling it to collect in the bottom of the cup. Thee bottom of cup 30 has an opening 62 which contains a conventional fitting 64 having a drain cock 66.

Baffle ring 50 has a circumferentially arranged series of passages 68 around its periphery through which air flows en route from inlet 44 to expansion chamber 52. In the form of the invention illustrated, these passages are defined by. grooves circumferentially separated by vanes 70. The grooves have helical configuration with cross dimension. Ring 50 has a flange 72adjacent its top which seats on the top edge 74 of cup 30. Vanes engage against upper wall portions 48 of the cup so that these wall portions and the vanes cooperate to close the radially outer portions of passages 68.

Baffle ring 50 has an annular partition wall 76 radially inward of grooves 68 and an annular skirt 78 spaced radially inwardly of partition 76. Partition 76 and skirt 78 define therebetween an annular gap 80 which has a closed upper end 82 and which opens vertically downwardly into expansion chamber 52. Partition 76 separates grooves 68 from gap 80. The partition and skirt 78 have bottom surfaces 84 and 86 respectively which preferably lie substantially on a common horizontal plane.

Skirt 78 has a tubular extension 88 which extends upwardly from baffle ring 50 per se and, fits within an opening 90 in head 28. Opening 90 has an annular, radially inward shoulder 92 and from the shoulder continues axially upwardly at 94 through the top of head 28. Generally speaking, extension 88 and upper opening portion 94 may be regarded as the outlet from expansion chamber 52.

A muffler 96 is mounted in the outlet. In the illustrated form of the invention this muffler comprises a pair of truncated conical porous sintered metal elements 98. These elements are hollow having closed ends 100 and open bases 102. Bases 102 have interengaged, radially outward flanges 104 disposed beneath shoulder 92 in head 28 and above top 106 of extension 88. An axially compressible spring 108 is provided between end 106 and base flanges 104. Spring 108 may comprise a conventional, radially slit ring having vertical waves therein. When ring 32 is tightened, top 74 of cup 30 urges flange 72 and extension 88 upwardly, compressing spring 108 and urging the top one of interengaged flanges 104 against shoulder 92 to secure muffler elements 98 in position. Top 106 has a notch which contains a seal washer 110 engaged against opening 90 in head 28.

In use, silencer and lubricant trap 24 is mounted in a generally vertical position as shown with exhaust air line 22 threaded into inlet 44. When air is exhausted from cylinder it passes through line 22 and into circumferential passageway 46. The air flows downwardly through passages 68 in baffle ring 50 and into expansion chamber 52. Passages 68 have a considerable length and this length combined with their helical orientation imparts a whirling movement to the air flowing therethrough. When the air exits from passages 68 it both expands and is flung outwardly by the centrifugalforce of its whirling movement. The air impinges downwardly and outwardly against the wall of expansion chamber 52 and most of the lubricant carried from cylinder 10 into the expansion chamber becomes deposited upon the expansion chamber wall. Most of the deposited lubricant drains downwardly through openings 60 in baffle 66 and collects in the bottom of sump chamber 54. t

From chamber 52 the air passes through the myriad pores in lower muffler element 98, passes upwardly through the hollow interiors of the muffler elements and then outwardly through the myriad pores in upper muffler element 98 to the atmosphere. Some of this air passes directly into that part of the lower muffler element which depends into chamber 52. Some of the air also flows upwardly along portions 112 of cup 30 beneath baffle ring 50, then radially inwardly past skirt 78, and then upwardly along the interior surface 114 of tubular extension 88.

If it were not for gap 80, some of the lubricant deposited at upper wall portions 112 would be propelled upwardly to baffle ring 50, across the bottom surfaces of the baffle ring, around the inner corner of skirt 78, and upwardly along tubular surface 114. This lubricant would be blown through muffler elements 98 and would be discharged'into the atmosphere. The reason for this is that the lubricant characteristically wets the surface on which it is deposited. That is to say, the lubricant spreads out in a thin fllm on the surface and this film is propelled along the surface by the air flowing thereover.

Gap 80, however, intercepts this flow of lubricant and also causes turbulence in the air flowing thereacross which interrupts the propelling force of the air on the lubricant. The closed upper end of the gap furthermore provides a relatively dead air space and virtually no lubricant is blown around the surface of this space. Consequently. very little of the lubricant traverses gap 80 to surfaces 86 and 114 from which it could otherwise be propelled upwardly and out of head .28 in the mannerdescribed. The intercepted lubricant accumulates on bottom surface 84 of partition 86 and when the accumulation is great enough, it drops downwardly into cup 30.

It is important that skirt 86 be short enough so that it is protected against impingement of lubricantbearing air issuing from passages 68. Otherwise, lubricant would be deposited directly thereon and would be propelled out of head 28 in the manner described.

The flow of air exiting from silencer and lubricant trap 24 is slowed and diffused into myriad paths by the porous material of muffler elements 98. The effect is to greatly reduce the volume of sound of the air discharging to the atmosphere.

In a typical silencer and lubricant trap 24 according to the present invention, grooves or passages 68 are lubricant carried into it by exhaust air through pipe 22.

In the same range of pressures the sound of the exhausting air is muffled down tov 104 to 105 decibels peak impact, A scale. The total air-exhaust time is about 12 to 12.] cycles (l cycle being l/60 second) utilizing compressed air at about m psi.

Cup 30, ring 32, baffle 56, and muffler elements 98 are standard items used in airline accessories such as lubricators, filters, and moisture traps. Head 28 is also a standard item except that it is modified to receive baffle ring 50, its extension 88 and muffler elements 98 and is also modified to isolate from the internal air flow path an opening 116 which forms a part of the air flow path in other airline accessories. Baffle ring 50 and extension 88 typically are made integrally from a plastic material such as a polycarbonate.

A silencer and lubricant trap 24 according to the present invention is thus relatively inexpensive and is very effective for its intended purposes.

I claim:

1. A silencer and lubricant trap for air exhausting from pneumatically powered tools which comprises,

means forming a body having an inlet adapted to receive air exhausted from a pneumatic tool, said body defining an expansion chamber having a wall, a passageway between said inlet and chamber, a lubricant sump below said chamber, and an outlet downstream of said chamber, I

baffle means in said passageway effective to direct air flowing therethrough into lubricant-depositing impingement against the expansion chamber wall,

muffler means effective to muffle the sound of air passing through said outlet,

there being surface portions within said body along which air flows toward said outlet, and at least one gap between certain of said surface portions surrounding the path of said air flow.

said gap being so dimensioned and positioned as to intercept lubricant propelled toward said outlet along those of said surface portions upstream of said gap,

said baffle means comprising a circumferentially arranged series of alternate webs and passages dimensioned and positioned to so divert air flowing through said passages,

said baffle means, said certain surface portions, and

i said gap comprising elements of an assembly,

said webs and passages being disposed around the periphery of said assembly,

said assembly having a partition which interconnects said webs, forms inner surfaces of said passages, and forms an out er side of said gap, said assembly having a skirt which is spaced from said partition and forms the inner side of said gap.

2. The structure defined in claim 1 wherein said passages have a length in the direction of air flow there through which is greater than their cross dimension.

3. The structure defined in claim 2 wherein said passages have helical form and are oriented to effect cen- 6. The structure defined in claim 5 wherein said webs comprise vanes engaged against portions of a wall defining said passageway and forming outer peripheral portions of said passages.

7. The structure defined in claim 6 wherein said body comprises a head and a cup, said head having said inlet and an upstream part of said passageway,

said cup being secured to said head and defining a downstream part of said passageway, said chamber and lubricant sump,

said vanes having flanges secured against the top of said cup by interengaged means on said head and assembly.

8. The structure defined in claim 7 wherein said assembly is annular and has a tubular extension of said skirt extending downstream therefrom, said interengaged means including the downstream end of said extension and means on said head.

9. The structure defined in claim 8 wherein said muffler means comprises at least one porous, sintered metal member having a peripheral portion contained between said downstream end of said extension and said means on said head.

10. The structure defined in claim 9 wherein there are a pair of said members having generally conical shape with interengaged flanged bases, the flanges of which are so contained between said downstream end and means on said head.

ll. The structure defined in claim 10 wherein a generally conical portion of one of said members projects through said extension into said expansionchamber, and a generally conical portion of the other of said members projects away from the outlet and exteriorly 6 of said head.

12. The structure defined in claim 8 wherein said assembly comprises a body of plastic material, said elements and tubular extension being integrally formed in said body of material.

13. A silencer and lubricant trap for air exhausting from pneumatically powered tools which comprises,

means forming a body having an inlet adapted to receive air exhausted from a pneumatic tool,

said body defining an expansion chamber having a wall, a passageway between said inlet and chamber, a lubricant sump below said chamber, and an outlet downstream of said chamber,

baffle means in said passageway effective to direct air flowing therethrough into lubricant-depositing impingement against the expansion chamber wall, there being surface portions within said body along which air flows toward said outlet, and at least one gap between certain of said surface portions surrounding the path of said air flow,

said gap being so dimensioned and positioned as to intercept lubricant propelled toward said outlet along those of said surface portions upstream of said gap,

said-baffle means, said certain surface portions, and

said gap comprising elements of an assembly,

said outlet being open to atmosphere, muffler means effective to muffle the sound of air passing through said outlet to atmosphere,

said body and assembly having support means which secure said muffler within said outlet.

14. The structure-defined in claim 13 wherein said muffle has a portion which projects into said expansion chamber and a portion which projects beyond said outlet to the exterior of said body.

15. The structure defined in claim 14 wherein said muffler is formed of a porous sintered metal and is hollow.

16. The structure defined in claim 15 wherein each of said muffler portions has the form of a truncated cone with a base, the bases of the cones having interengaged flanges, said flanges being engaged by said support means. 

1. A silencer and lubricant trap for air exhausting from pneumatically powered tools which comprises, means forming a body having an inlet adapted to receive air exhausted from a pneumatic tool, said body defining an expansion chamber having a wall, a passageway between said inlet and chamber, a lubricant sump below said chamber, and an outlet downstream of said chamber, baffle means in said passageway effective to direct air flowing therethrough into lubricant-depositing impingement against the expansion chamber wall, muffler means effective to muffle the sound of air passing through said outlet, there being surface portions within said body along which air flows toward said outlet, and at least one gap between certain of said surface portions surrounding the path of said air flow, said gap being so dimensioned and positioned as to intercept lubricant propelled toward said outlet along those of said surface portions upstream of said gap, said baffle means comrising a circumferentially arranged series of alternate webs and passages dimensioned and positioned to so divert air flowing through said passages, said baffle means, said certain surface portions, and said gap comprising elements of an assembly, said webs and passages being disposed around the periphery of said assembly, said assembly having a partition which inter-connects said webs, forms inner surfaces of said passages, and forms an outer side of said gap, said assembly having a skirt which is spaced from said partition and forms the inner side of said gap.
 2. The structure defined in claim 1 wherein said passages have a length in the direction of air flow therethrough which is greater than their cross dimension.
 3. The structure defined in claim 2 wherein said passages have helical form and are oriented to effect centrifugal impingement of said air against said chamber wall.
 4. The structure defined in claim 3 wherein said passages have substantially uniform effective sectional area throughout their lengths.
 5. The structure defined in claim 1 wherein said partition and skirt terminate in a downward direction substantially at a common horizontal plane and have bottom surfaces comprising said certain surface portions.
 6. The structure defined in claim 5 wherein said webs comprise vanes engaged against portions of a wall defining said passageway and forming outer peripheral portions of said passages.
 7. The structure defined in claim 6 wherein said body comprises a head and a cup, said head having said inlet and an upstream part of said passageway, said cup being secured to said head and defining a downstream part of said passageway, said chamber and lubricant sump, said vanes having flanges secured against tHe top of said cup by interengaged means on said head and assembly.
 8. The structure defined in claim 7 wherein said assembly is annular and has a tubular extension of said skirt extending downstream therefrom, said interengaged means including the downstream end of said extension and means on said head.
 9. The structure defined in claim 8 wherein said muffler means comprises at least one porous, sintered metal member having a peripheral portion contained between said downstream end of said extension and said means on said head.
 10. The structure defined in claim 9 wherein there are a pair of said members having generally conical shape with interengaged flanged bases, the flanges of which are so contained between said downstream end and means on said head.
 11. The structure defined in claim 10 wherein a generally conical portion of one of said members projects through said extension into said expansion chamber, and a generally conical portion of the other of said members projects away from the outlet and exteriorly of said head.
 12. The structure defined in claim 8 wherein said assembly comprises a body of plastic material, said elements and tubular extension being integrally formed in said body of material.
 13. A silencer and lubricant trap for air exhausting from pneumatically powered tools which comprises, means forming a body having an inlet adapted to receive air exhausted from a pneumatic tool, said body defining an expansion chamber having a wall, a passageway between said inlet and chamber, a lubricant sump below said chamber, and an outlet downstream of said chamber, baffle means in said passageway effective to direct air flowing therethrough into lubricant-depositing impingement against the expansion chamber wall, there being surface portions within said body along which air flows toward said outlet, and at least one gap between certain of said surface portions surrounding the path of said air flow, said gap being so dimensioned and positioned as to intercept lubricant propelled toward said outlet along those of said surface portions upstream of said gap, said baffle means, said certain surface portions, and said gap comprising elements of an assembly, said outlet being open to atmosphere, muffler means effective to muffle the sound of air passing through said outlet to atmosphere, said body and assembly having support means which secure said muffler within said outlet.
 14. The structure defined in claim 13 wherein said muffle has a portion which projects into said expansion chamber and a portion which projects beyond said outlet to the exterior of said body.
 15. The structure defined in claim 14 wherein said muffler is formed of a porous sintered metal and is hollow.
 16. The structure defined in claim 15 wherein each of said muffler portions has the form of a truncated cone with a base, the bases of the cones having interengaged flanges, said flanges being engaged by said support means. 